Transformer gasket structure



\ y 24, 1956 J. A. MCDONNELL 2,756,270

TRANSFORMER GASKET STRUCTURE Filed Dec. 30, 1952 Inventor: John A.McDonnell,

Jo y WfiTM His Abtorne s.

United States Patent Office 2,756,270 i atented July 24, 1956 2,756,270TRANSFORMER GASKET STRUCTURE John A. McDonnell, Nahant, Mass., assignorto General Electric Company, a corporation of New York ApplicationDecember 30, 1952, Serial No. 328,729 2 Claims. (Cl. 174-52) Thisinvention relates to transformer gasket structures and more particularlyto a new and improved gasket structure for a cover over an opening orrecess in a transformer casing which is made of resilient rubber-likematerial.

Gaskets, in the form of cork or rubber-like rings, are often interposedbetween a rim or flange surrounding an opening or recess in atransformer casing and a cover for such opening in order to provide atight seal when suitable cover fastening means is tightened so as tocompress the gasket material. Sometimes the casing itself is made ofresilient rubber-like material. For example, some electrical instrumenttransformers have their electromagnetic parts insulatingly embedded andresiliently supported in a molded butyl rubber casing which has a siderecess for secondary winding terminals, which recess it is desirable toclose tightly by means of a sealed but removable cover. One problem inconnection with such a construction is that of removably attaching thecover tightly enough so that a gasket seal can be made. In accordancewith this invention, a rigid backing member is located adjacent to theopening to be covered in the resilient casing material in such a mannerthat the portion of the resilient material surrounding the opening isclamped between the cover and the backing member and thus constitutes anintegral built-in gasket.

An object of the invention is to provide a new and improved transformergasket structure.

Another object of the invention is to provide a novel and simpleintegral built-in gasket structure for an opening or recess in atransformer casing which is made of resilient rubber-like material.

The invention will be better understood from the following descriptiontaken in connection with the accompanying drawing and its scope will bepointed out in the appended claims.

In the drawing Fig. l. is a front elevation partly in section of aninstrument current transformer embodying the invention, and Fig. 2 is aside elevation partly in section of the transformer shown in Fig. 1.

Referring now to the drawing, the transformer is indicated generally bythe reference numeral 1. Its internal electrical and magnetic parts (notshown) may be of conventional construction and they are insulatinglyembedded and resiliently supported in a molded casing 2 of resilientrubber-like material such as synthetic rubber of the butyl type. Theentire structure is rigidly supported on a metal base plate 3 to which apair of metal angle bar mounting brackets 4 are attached by bolts 5.

Extending from the top of the casing 2 are a pair of heavy currentcarrying high voltage terminals 6, the electrical insulating creepagedistance of which to the normally grounded metal supporting parts 3 and4 is increased by means of integral molded-in petticoats or flanges 7 inthe casing material. In other words, the upper part of the casingmaterial which is surrounded by the petticoat members 7 correspondsgenerally in function to a high voltage insulating bushing for the highvoltage terminals 6. Set into a recess or cavity 8 in the front of thelower or main body portion of the casing 2 is a low voltage secondaryWinding terminal structure 9. The opening for the recess 8 is closed bya cover member 10.

Cooperating with the cover member 10 for the purpose of attaching thecover member firmly and removably in place and also making a tight sealbetween the cover member and the casing, there is provided a rigidbacking member 11 preferably in the form of a metal ring or frame havingan integral angularly extending bottom flange or foot 12 which may beattached to the main supporting plate 3 in a suitable manner such as byspot welding. When the housing or casing material is molded, it maysurround the frame or backing member 11 so that the latter may also beembedded in the portion of the resilient casing material which surroundsthe opening for the cavity 8. Thus, it will be seen that there is aportion 13 of the resilient rubber-like casing material which is betweenthe backing plate 11 and the cover 10 and which constitutes an integralbuilt-in gasket for the cover 10.

The cover may be fastened in place by any suitable means such as by thefour thumb screws 14 which have been illustrated. As shown, these extendbetween the cover 10 and the backing plate 11 and pass through thesuitable holes in the built-in integral gasket 13 so that when they aretightened, they will compress the built-in integral gasket 13 and thusform a tight seal.

While there has been shown and described a particular embodiment of theinvention, it will be obvious to those skilled in the art that variouschanges and modifications may be made without departing from the spiritand scope of the invention and I, therefore, aim by the appended claimsto cover all such changes and modifications as fall within the truespirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In an instrument current transformer, a solid casing of resilientrubber-like material in which electromagnetic parts are insulatinglyembedded and resiliently supported, a recess for secondary windingterminals in a side of said casing, a cover for said recess having a rimwhich corresponds in surface configuration to the part of the surface ofsaid casing which surrounds the opening to said recess, a rigid backingring embedded in said resilient rubber-like material under said part ofthe surface of said casing, said electro-magnetic parts and said backingring being embedded in said casing during the molding thereof andthreaded fastening means extending between said cover rim and backingring for clamping therebetween a portion of said resilient rubber-likecasing material so that said portion constitutes an integral built-ingasket which provides a water-tight seal for said cover.

2. In an instrument current transformer, a solid casing of resilientrubber-like material in which electromagnetic parts are insulatinglyembedded and resiliently supported, a flat sheet metal base for saidcasing, a recess for secondary winding terminals in a side of saidcasing, a cover for said recess having a rim which corresponds insurface configuration to the part of the surface of said casing whichsurrounds the opening of said recess, a rigid backing ring embedded insaid resilient rubber-like material under said part of the surface ofsaid casing, said electro-magnetic parts and said backing ring beingembedded in said casing during the molding thereof said backing ringhaving an integral angularly extending mounting foot attached to saidsheet metal base, and threaded fastening means extending between saidcover rim and backing ring for clamping therebetween a portion of saidresilient rubber-like casing material so that said portion constitutesan integral built-in resilient gasket which provides a water-tight sealfor said cover.

References Cited in the file of this patent UNITED STATES PATENTS1,335,467 Traynor Mar. 30, 1920

1. IN AN INSTRUMENT CURRENT TRANSFORMER, A SOLID CASING OF RESILIENTRUBBER-LIKE MATERIAL IN WHICH ELECTROMAGNETIC PARTS ARE INSULATINGLYEMBEDDED AND RESILIENTLY SUPPORTED, A RECESS FOR SECONDARY WINDINGTERMINALS IN A SIDE OF SAID CASING, A COVER FOR SAID RECESS HAVING A RIMWHICH CORRESPONDS IN SURFACE CONFIGURATION TO THE PART OF THE SURFACE OFSAID CASING WHICH SURROUNDS THE OPENING TO SAID RECESS, A RIGID BACKINGRING EMBEDDED IN SAID RESILIENT RUBBER-LIKE MATERIAL UNDER SAID PART OFTHE SURFACE OF SAID CASING, SAID ELECTRO-MAGNETIC PARTS AND SAID BACKINGRING BEING EMBEDDED IN SAID CASING DURING THE MOLDING THEREOF ANDTHREADED FASTENING MEANS EXTENDING BETWEEN SAID COVER RIM AND BACKINGRING FOR CLAMPING THEREBETWEEN